Interventions addressing cost-related medication nonadherence in diabetes: a scoping review

One in 6 patients with diabetes in the US reports rationing or abandoning their medications to save costs. Our objective was to describe the breadth, approach, and impact of interventions that sought to address cost-related nonadherence among patients with diabetes in 2003-2023. Studies were eligible if they were published in English, pertained to diabetes, described interventions or policies that reduced or eliminated diabetes medication costs, and evaluated medication adherence as a primary or secondary outcome. We identified studies using MEDLINE, Embase, and Scopus. Two independent reviewers assessed each article's abstract and full text in 2 phases; 29 articles met inclusion criteria. Sixteen interventions reduced diabetes-related co-payments: Seven found improvements in adherence, 6 found no improvement, and 3 did not evaluate changes over time. Eight interventions eliminated all or some diabetes-related costs: Five found improvements in adherence, 2 found no improvement, and 1 did not evaluate changes over time. Interventions that combined cost-reduction or cost-elimination strategies with wellness and disease management programs tended to lead to improved short- and long-term adherence. Six articles evaluated statewide or federal policies (eg, insulin co-payment caps), with varying effects on adherence. Interventions that eliminate diabetes-related costs and provide additional diabetes management assistance may improve access and adherence to medications. Additional work is needed to evaluate the impact of these interventions on long-term health and utilization outcomes.